The present invention relates to axial retaining members and more particularly to a unitary axial retaining member for interconnecting two components and preventing axial motion therebetween. The present invention is particularly useful for preventing relative axial motion between a female member, such as an inner race of a half-shaft assembly, and a shaft inserted in a bore in the female member.
There are many mechanical structures requiring the interconnection between a shaft and a female member having a bore for the shaft. Often, what is desired is a structure for preventing relative axial motion between the shaft and the female member. An example of a device requiring such a structure is a half-shaft assembly used in the drive train of a front wheel drive automobile. Typically, a shaft is provided which is inserted in a bore in an inner race. Cooperating splines are provided between the shaft and the inner race to prevent relative rotation therebetween.
Typically, two or more fastening members are used for interconnecting the shaft and the inner race. A first fastening member may be a retainer ring disposed ahead of the splines on the shaft and forced by the splines into a retaining position below the minor diameter of the inner race splines. In this position, the retaining ring expands into a groove in the inner race and separation of the shaft from the inner race is prevented. However, a certain amount of movement of the shaft relative to the inner race is still possible.
A second retaining member consisting of a spacer ring may also be provided, the spacer ring being fitted in an annular bore on the shaft and abutting a portion of the inner race so as to prevent further movement of the shaft into the bore in the inner race. Thus, the spacer ring cooperates with the retaining ring to prevent movement of the shaft relative to the inner race in either direction.
A chamfer angle is machined at the bottom of a counterbore of the above described bore and this chamfer angle acts in a wedge-like fashion, compressing the retaining ring inwardly and thus facilitating disassembly. This chamfer angle must be carefully selected to avoid inadvertent disconnection of the assembly during use, yet to permit disassembly when required for service.
The use of two separate retaining elements, as described above, is expensive and inconvenient. Accordingly, what is needed is a unitary axial retaining member to replace the two or more retaining members previously used.
A prior design for a unitary retaining means is described in U.S. Pat. No. 3,832,076, to Glenn Gehrke. The retaining ring disclosed therein is used to interconnect a male and female splined member. The female member has an annular radially inwardly facing retaining groove that is located radially opposite an annular radially outwardly facing retaining groove on the male member when the splined members are in the desired mating relationship. The splined members are retained together by a retaining ring of the snap ring type which is split and may be positioned such as to occupy both the retaining grooves when the grooves are radially aligned. The size of the retaining ring is determined so that the retaining ring is expanded against the bottom of the retaining groove and is in interference contact with the splines between their major and minor diameters. The retaining ring is urged by ramps on one end of the splines of one of the members into an assembly-dissembly position in an annular groove on the other member. Upon proper mating of the members, the retaining ring assumes a retention position in the grooves. However, one of the grooves is ramped on one side to provide disassembly by reversal of the assembly operation. Accordingly, the retaining ring described above does not positively connect the female splined member with the male splined member and, accordingly, inadvertent disassembly during use is possible under extreme conditions.
Various other designs have been developed in the past for interconnecting splined elements. For example, U.S. Pat. No. 3,527,120 to M. J. Duer, et al., teaches a differential and axle shaft retainer which includes a spring member retained on the axle shaft by tangs engaging a groove formed on the shaft. The body of the retainer is flexible outwardly for installation on the axle shaft and flexes inwardly so as to permit sliding of the axle shaft through the differential case and side gear openings into its installed position. Upon installation, the retainer fingers spring outwardly into engagement with the abutting surfaces of the side gears so as to lock the axle shaft in position and prevent outward axial movement thereof.
Brown, U.S. Pat. No. 2,089,168 as well as Hawkins, U.S. Pat. No. 3,449,926 both teach a means for locking a nut or hub member to a shaft. In Brown, a hub having splines with one side parallel to the hub axis and another side tapered is mounted to a splined shaft with parallel splines utilizing an intermediate member having fingers which have been machined to cooperate between the splines of the hub and shaft member. The fingers on the intermediate member are parallel to the axis on one side and tapered on the other side so that when the hub and intermediate member are mounted to the shaft, a nut is tightened against the intermediate member such that the fingers engage the tapered sides of the hub splines and carry the hub along until it abuts against the spacer. Further tightening of the nut then accomplishes two results. First, the tapered fingers are wedged circumferentially in the tapered spaces between the hub splines and the shaft splines. Second, the axial pressure from the nut also forces the hub firmly against the spacer, thus, clamping the bearing race against the shoulder. This assembly provides a tight circumferential driving fit between the hub and the shaft.
In Hawkins, a turbine shaft is coupled to the shaft of a compressor drive utilizing a thrust nut which prevents any relative rotation of the thrust nut and the shaft to which it is threaded, and which is readily adjustable by a tool inserted through one shaft. A safety interlock is provided such that the tool cannot be removed after the nut has been adjusted unless it has been stopped at the position where the detent is effective. Accordingly, the coupling is an axially adjustable connection between coaxial shafts. In this coupling, the fingers serve to couple the nut to a locking device or lock ring. A plurality of wave springs and ring members are built up on the thrust nut which includes the part extending axially defined by fingers to nonrotatively lock the ring to a shaft. The snap ring groove extends around the rear end of the fingers to receive a snap ring and thereby lock the wave springs and ring members to the thrust nut.
Smith, U.S. Pat. No. 2,625,415, teaches a flexible splined connection for a pair of members in which one of the members is provided with a plurality of integral, independently flexible longitudinally extending keys or fingers which are expanded in such a manner to ensure contact over the entire contact area of a mating spline passage. The longitudinally extending keys or fingers are manufactured by slotting or cutting the splined end of the shaft and expanded radially by applying pressure to the ring at the base portion of the recess so that the outer diameter of the circumferentially spaced keys is slightly larger than the diameter of the spline passage. Upon assembly, the keys are individually flexed inwardly a slight amount and when in position, each individual key contacts a portion of the adjacent keys and its mating keyway in the hub to thereby maintain even contact and constant pressure along the entire length and diameter of the passage. Prior to forming the splines on the shaft, an outer annular ridge is machined on the shaft of such dimension as to fit within the recess. It is interesting to note for this particular application, the splined end of the shaft must protrude beyond the hub member in order to enable disassembly from the shaft. In fact, this was specifically set forth in Column 3 of the Smith patent.
None of these prior designs, however, address the basic problem described above, that is, providing a simple, inexpensive, unitary retaining member for positively axially retaining a shaft to an inner race of a half-shaft assembly.